Hi there. Good luck with the brew! Wort in an FV on a concrete floor will likely be colder than the room temp, apart from at peak activity, which you may well realise
What yeast are you using? I had WLP300 right down to 57f, at which temperature it was bereft of any banana at all. Decent beer, but I prefer some banana in there. I have my second hefe fermenting at a constant 66f right now, and that has thrown out huge banana smells and a escaped the FV after 20hrs!